Soon-to-be celebrity jailbird Lindsay Lohan has taken a swipe at the American criminal justice system in a series of messages posted on social networking site Twitter.

The 24-year-old actress, who was yesterday sentenced to 90 days in jail and 90 days in rehabilitation for violating probation on two drink-driving charges, appeared to criticise the court system for not treating offenders as individuals in sentencing.

"November 1 marked the 15th anniversary of the U.S. Sentencing Guidelines," the article states.

"But there were no celebrations, parades, or other festivities in honor of this punishment scheme created by Congress and the U.S. Sentencing Commission.

"Instead, the day passed like most others during the last 15 years: Scores of federal defendants sentenced under a constitutionally perverted system that saps moral judgment through its mechanical rules."

The actress broke down twice during her sentencing hearing; once during a direct appeal to Superior Court Judge Marsha Revel and again when Judge Revel meted out Lohan's punishment.

If Lohan had read to the end of the article, however, she might have noticed that the author argued for the very flexibility Judge Revel employed.

"Only judges can mete out punishment that fits both the offense and the offender, mindful of the deeply held notion that government must treat each individual as unique rather than just another object on the conveyor belt of sentencing."

The actress also posted a link to a Newsweek article about Iranian woman Sakineh Mohammadi Ashtiani, a mother-of-two who faces being stoned to death for adultery.

And she quoted Article 5 in the United Nations' Universal Declaration of Human Rights, which states: "No one shall be subjected to torture or to cruel, inhuman or degrading treatment or punishment".

Those Tweets followed an attempt to clarify the intention behind the actress's colourful manicure in court the day before, which included obscene messages on each of her middle fingers.

Close-up photos taken by a courtroom photographer revealed the tiny letters, which made worldwide news.

Were the messages intended for the judge, who levied the harsh sentence Tuesday? Directives to the ever-present paparazzi who follow Lohan's every move? Perhaps a silent snub to her estranged father, who attended Tuesday's proceedings?

"Didn't we do our nails as a joke with our friend dc?" Lohan asked a friend on Twitter.

Written expression on her hands is nothing new, though. Lohan also has a tattoo on her right index finger that reads "Shhh..."

Her criminal defence lawyer, Shawn Chapman Holley, who sat beside the actress during Tuesday's hearing, was in court on Wednesday and not immediately available to comment on the naughty nails.

Ed McPherson, Lohan's civil lawyer who attended Tuesday's hearing and sat near her in court during breaks, said he did not notice the message painted on her fingernails and does not think she meant to disrespect the court.

"Absolutely not," he said.

He said Lohan's tearful statement in court was sincere.

"I think she thinks that she's come a long way," he said.

"Obviously she's very upset about this."

The actress had some good news on Wednesday.

A probation report said her six drug screenings since May were clean of illicit drugs and alcohol.

The reports showed the screenings occurred after the actress missed a court hearing and a judge imposed new restrictions, including wearing an ankle alcohol monitor.

The report was released a day after the judge sentenced Lohan to 90 days in jail and a stint in rehab for missing court-mandated alcohol education classes.

The report showed Lohan was taking a variety of medications for which she had valid prescriptions, and their use did not constitute a probation violation.

In addition, the "Mean Girls" star got a reprieve Wednesday in another pending court case when a judge delayed a civil trial stemming from one of Lohan's 2007 arrests.

Her lawyers and four people suing her agreed to delay a trial scheduled for later this month, citing her upcoming jail sentence, which is set to begin July 20.

No new date for the civil trial was set.

Lohan is being sued by a woman who was in a vehicle chased by the actress and three other men who claim Lohan involved them by taking a sport utility vehicle without permission.

Both sides have listed Lohan as a potential witness during the trial.

Lohan must wear an alcohol-monitoring anklet until she surrenders for jail later this month.

After completing her time behind bars, she has two days to report to a probation officer to begin formal probation.

She is also required to spend 90 days in an inpatient substance-abuse program.

The back-to-back sentences are likely to prevent Lohan from promoting her fashion line, 6126, which begins shipping out to stores this month, and the Robert Rodriguez movie Machete, set to open in September.

The sentence will also delay production of Inferno: A Linda Lovelace Story, in which Lohan stars as the title character.